Originally Posted by slvrbrt 
Tightening the fill and drain plugs will not keep out water, it gets sucked in past the seals as the diff heats and cools. I generally check mine after most rides, and there is almost always water.
The front diff is the weak point on the Kawi quads, but they hold up ok if treated right. That said, I have blown up a couple of them. I no longer try to launch out of mud holes with the front end slamming back onto the ground at full throttle.
Also, started running the wetbrake fluid in the front, same as in the rear, seems to make for nicer action on the difflock.
that's an interesting bit of info.